Physiological And Biochemical Response Characteristics Ofcunninghamia Lanceolatato Soil Warming In The Middle Subtropical Zone At Different Seasons

The burning of large amounts of fossil fuels and changes in the way of land use have caused the atmospheric temperature to rise.Vegetation is a natural link linking elements such as atmosphere,water and soil.It belongs to the variable temperature type.The interaction process between climate and vegetation is an important link in the process of land ecosystem.Subtropics is a transitional zone between the temperate zone and the tropics.It has a special location and may be more sensitive to the temperature change.It is not clear whether plants in different seasons have different responses to physiological and ecological responses to warming.Therefore,it is particularly necessary to study the effects of warming in different seasons on the physiological and ecological characteristics of plants in the middle subtropics.This research is located at Sanming forest ecosystem and global change research station in Sanming,Fujian,Dalin national forest farm.There are two treatments:experimental setup control(CT)and warming up(W).Each treatment has 5 replicates,a total of 10 quadrats,which is heated by cables.In December 2016 and July 2017 sampling,carbon nitrogen phosphorus and potassium content determination of calcium and magnesium in leaves of Chinese fir,explore the nutrient use;in addition,the growth of Chinese fir by photosynthesis,peroxide,antioxidant enzyme activity,endogenous hormones and other indicators,explore different seasons warming effects on Physiological Ecology of Chinese fir,in order to reveal the growth strategy of global warming under the background of Chinese fir the.Following is the main conclusions of this paper:1)After warming,the contents of total organic carbon,total nitrogen,total phosphorus,potassium,calcium and magnesium all showed a decreasing trend.The soil available nitrogen mainly existed in the form of NH4+,and NO3-/NH4+decreased significantly after warming,and the soil ?15N did not increase.The result showed that the research area was in the nitrogen restriction state.2)Our experiment tree is Cunninghamia lanceolata seedling trees which is in rapid growth stage.And the nitrogen and phosphorus contents of leaves decreased after warming,indicating that short-term warming was not conducive to plant nutrient accumulation.Warming increased N/P and ?15N of leaves,leaf N/P is still less than 14,and higher in non-growing season,?15N is same.This means Cunninghamia lanceolata is still in the state of nitrogen limitation,warming can alleviate the nitrogen limitation,and warming in non-growing season works better than in growing season.3)Warming increased the content of ROS in leaves.Plants can scavenge ROS by increasing Pro and GSH content and SOD,CAT and GSH-Px activity in non-growing season,while by increasing the soluble protein concentration,GSH content and POD,APX and GSH-Px activity in growing season.The activity of T-AOC is higher after warming and lower in growing season,which corresponds with the content of MDA.This means warming has caused damage to the physiological state of Cunninghamia lanceolata,the stress is more obvious in growing season.Warming has no significant effect on the synthesis of auxin.4)After warming,leaf net photosynthetic rate(Asat)decreased significantly,dark respiration rate(Rara)did not change significantly,the ratio of respiration and photosynthetic(Rarea/Asat)has increased,and significantly higher in July than in May and October.The content of nonstructural carbohydrate(NSC)in leaf showed a corresponding change.The results show that higher temperature is not conducive to the accumulation of organic matter in Cunninghamia lanceolata.At the set temperature(25?),the potential maximum net photosynthetic rate(Amax25)decreased significantly after warming.The content of leaf nitrogen and NSC play an important role on leaf photosynthetic capacity changes.While dark respiration rate(Rarea25)did not change significantly compared to control treatment.This means Rarea25 has adapt to temperature changes,and the content of NSC plays an important role in this process.